Recently, compact and thin image pickup apparatuses each employing a solid-state image pickup element such as a CCD type image sensor and a CMOS type image sensor have come to be mounted on mobile terminals being compact and thin electronic devices such as a cell phone and PDA (Personal Digital Assistant), and further on note PCs, which allows mutual transmission not only of sound information but also of image information to a remote location. Such the image pickup apparatuses are strongly demanded to be downsized and to handle high quality images realizing image quality expected by users.
A solid-state image pickup element and an image pickup lens are main components constructing an image pickup apparatus. As a solid-state image pickup element, many apparatuses use a device such as a CCD type image sensor and a CMOS type image sensor, In recent years, downsizing of pixel pitch of a solid-state image pickup element has been advanced, and high resolution and high performance are being achieved by using the increased number of pixels. On the other hand, downsizing of a solid-state image pickup element is being achieved by keeping the number of pixels.
In view of those, an image pickup lens which has a three-lens structure and includes a first lens and second lens both having positive power, has been proposed as disclosed in Patent Literature 1. Further, an image pickup lens wherein a second lens is negative has been proposed as shown in Patent literatures 2 to 4.